We investigated the changes of matrix metalloproteinase (MMP) -9 in the peripheral blood samples of patients undergoing endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms (AAAs), and the effect of azelnidipine on plasma MMP-9 levels in those patients. Levels of MMP-9 were measured in 22 patients who underwent EVAR for AAAs, and results were compared between a group receiving 16 mg azelnidipine daily (n=12) and a control group without azelnidipine (n=10). Measurements were taken preoperatively, and at 1 month and 3 months, postoperatively. Patients without endoleaks after EVAR showed a significant decrease in mean plasma MMP-9 levels (preoperative value: 39.5+/-14.3 ng/mL, after 1 month: 25.0+/-12.6, after 3 months: 28.2+/-10.2 ng/mL; P=0.004). In contrast, no significant decreases in mean plasma MMP-9 levels were observed in the patients with endoleaks after EVAR (preoperative value: 37.5+/-9.0 ng/mL, after 1 month: 26.8+/-8.4, after 3 months: 38.5+/-15.7 ng/mL; P=0.219). Moreover, among patients without endoleaks, those receiving azelnidipine showed a significantly greater decrease in the mean plasma MMP-9 levels for 3 months postoperatively (preoperative value: 47.7+/-13.2 ng/mL, after 1 month: 26.6+/-12.8, after 3 months: 26.1+/-11.4 ng/mL; P0.001) compared with the control group without endoleaks (preoperative value: 31.3+/-10.5 ng/mL, after 1 month: 33.4+/-12.1, after 3 months: 30.3+/-9.1 ng/mL; P=0.792). These results showed that azelnidipine treatment in patients without endoleak after EVAR was associated with a significant decrease in mean plasma MMP-9 levels for 3 months postoperatively.